The present invention relates to apparatus for feeding liquid adhesive to one or more consuming stations, and more particularly to improvements in apparatus which are especially suited to supply adhesive to the applicators of machines for the production and/or processing of smokers' products including plain or filter tipped cigarettes, cigarillos or cigars, cheroots, filter rod sections, and packs for cigarettes or the like. Still more particularly, the invention relates to improvements in apparatus for expelling entrapped air and/or other gases from a stream of adhesive which is caused to flow from a source of supply to one or more applicators.
Cigarette making machines, filter rod making machines and other types of machines for the production and/or processing of smokers' products employ so-called pasters which serve to apply films of adhesive to running webs of flexible sheet material, such as cigarette paper, imitation cork, reconstituted tobacco, strips of paper or lightweight cardboard which are to be converted into components of packs for smokers' products and the like. Conventional pasters employ wheel-shaped applicators whose peripheral surface receives a film of paste and rolls along the running web which is to be coated with adhesive, either in its entirety, along one or both marginal portions, along one or more intermediate portions, or along one or more marginal portions as well as along one or more intermediate portions. Such applicators are satisfactory as long as the speed of the web does not exceed a certain value. Therefore, many recent types of high-speed machines in the tobacco processing field, especially cigarette makers and filter rod makers, employ applicators in the form of nozzles which can discharge directed streams of liquid adhesive to one or more selected portions of a running web. The adhesive which is used in such machines is often highly viscous and is likely to contain entrapped bubbles of air or another gas. The presence of such bubbles in the stream of adhesive issuing from a nozzle is highly undesirable because the bubbles interrupt the films of adhesive which are applied to the running web. If the web consists of cigarette paper and is used for conversion into the tubular envelope of a cigarette rod, the absence of adhesive caused by gas bubbles results in weakening of the corresponding portions of the seam where the marginal portions of the tubular envelope of a cigarette rod overlap. Since the filler of a cigarette rod contains compacted tobacco, the weakened portion of the seam is likely to open, i.e., the wrapper of the respective cigarette develops a leak which is detected by the testing unit or units and the corresponding article is segregated from acceptable articles with resulting losses in output and tobacco. Thus, the presence of air bubbles in the stream of adhesive which is supplied to the applicator of a cigarette making or like machine presents serious problems which are not adequately solved by presently known degasifying apparatus or are solved, to a certain extent, by utilizing highly complex degasifying and/or adhesive preparing and processing equipment.